The current increase in day care centers raises serious questions concerning the mental health implications of this total child-care service. In an effort to clarify relationships between programs of centers, physical design and resultant patterns of facility utilization, a series of comparative studies of three day care centers has been undertaken. Through intensive observation and interview techniques of centers similar in program and clientele but differing in physical design, data are gathered on use patterns and the attitudes of occupants, over time. In addition, a format for planning and evaluation is being developed, including use of behavioral data in a comprehensive collaboration with parents, staff and architects.